Fluorescent lighting problem

[Ralphie]

We installed new electronic ballasts (f96t12 two tube fixtures) in the basement of a bakery. There are two rooms "A" and "B". With the lights in both rooms turned on ; Turn off the lights in room "B" they go out the flash back on for a fraction of a second,:huh: However if the lights in room "A" are off, the lights in room "B" perform normally. Why is this happening

 

[Dennis Alwon]

If they are electronic ballasts then you generally need to use T-8 bulbs or T-5 depending on the ballast- not T-12 bulbs

 

[ActionDave]

We installed new electronic ballasts (f96t12 two tube fixtures) in the basement of a bakery. There are two rooms "A" and "B". With the lights in both rooms turned on ; Turn off the lights in room "B" they go out the flash back on for a fraction of a second,:huh: However if the lights in room "A" are off, the lights in room "B" perform normally. Why is this happening

First question- Has the use of the space always been the same?

Second question- When you installed the new electronic ballast did you rewire the light fixture like the diagram on the new ballast shows?

 

[Ralphie]

Information on ballkast states it is suitable for f96T12 lamps. Ballasts are wired per diagram on the ballast. We have other similar installations but never had a problem like this. The wiring in this building is old, much of it NM cable without ground

 

[iceworm]

.... The wiring in this building is old, much of it NM cable without ground

Check the instructions with the ballast. The last electronic type I installed requuired a ground to function correctly.

ice

 

[jeremysterling]

If I've read the OP correctly:

When you turn the lights on, they come on.

When you turn the lights off, they flicker and go off.

So, you don't really have a problem, you're wondering why they flicker before they go off. Could be the ballast has to discharge a cap after power is removed. Could be a bonding issue as was already mentioned.

 

[Little Bill]

Information on ballkast states it is suitable for f96T12 lamps. Ballasts are wired per diagram on the ballast. We have other similar installations but never had a problem like this. The wiring in this building is old, much of it NM cable without ground

As has been mentioned, the electronic ballast require a ground to function properly. This setup with no ground might be worse if it's on a MWBC. Maybe the neutral in room A is acting as a ground when it is off, allowing room B to work right. This is just a guess other than the part about it needing to be grounded.

 

[goldstar]

If they are electronic ballasts then you generally need to use T-8 bulbs or T-5 depending on the ballast- not T-12 bulbs

That's not quite correct Dennis. I believe they no longer make magnetic ballasts so replacement ballasts are all electronic (even for T-12 bulbs). However, I was not aware that they are still manufacturing new fixtures with ballasts that would accommodate T-12 bulbs.

If you suspect that a missing ground might be your problem try an experiment and drag a piece of THHN over to a water line and temporarily ground the fixture to that pipe and see if the problem disappears.